Dash pot



M y 19, 1942- I J. IT.VMARSHALL 2, 5

' DASH POT Filed Aug. 26. 1941 Patented May 19, 1942 DASH POT John '1. Marshall, South Bend, Incl, assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application August 26, 1941, Serial No. 468,373

3 Claims.

This invention relates to rate controlling mechanisms and more particularly to a dash,

pot for use with a throttle valve, relay, or similar element to'be controlled in time.

held'in' a fluid-tight seal with flange II by means of an abutting flange I4, which is held tightly against diaphragm l3 by means of a plurality of stud screws l5. Flange M has a central dome- It is an object of the present invention to pro- 5 like portion l6 terminating in a screw-threadedvide a dash pot wherein loss of fluid is efiectively neck ll, which is capped by a screw closure l8, prevented. having a port IQ for the entrance of atmospher- It is an additional object of the present invenic air within the dome l6; Closure I8 also has a tion to provide a dash pot wherein the rate. of central bore 20, through which projects a rod: movement of the time controlling element. may 10 like arm member 2i, which extends within dome be adjusted, and wherein, by means of a flexi- 6, term t g in a flange portion and ble seal and self-contained unit, escape of fluid ing connected to a piston member 23. The end beyond the confines of thedash pot is prevented. of piston member 23 isscrew-threaded as at 24 Other objects will appearfrom a study of the to receive a nut 25 for connecting diaphragm following specification when made in conjuncm e 3 t0 piston 23,1116, fluid-tight s tion with the attached drawing, throughout Piston 23 is movable Within a ylin e 25 which like numerals designate like parts. formed longitudinally in housing Hi, and the left-.

Fig. 1 is a perspective view of a dash pot made hand portion of cylinder at terminates in an en-I in accordance with the present invention. larged Chamber recess Z Which is'mednt o Fig. 2 is a longitudinal sectional view of the holding a fluid, such as Oil t e e.- he m0 dash pot shown in Fig. 1. tion of piston 23 to the right is limited .by an Fig. 3 is a detailed view in perspective of a abutment 28 formed at the end of cylinder 26, sub-assembly of the dash pot shown in, Fig. 2; and motion of piston 23 to the left is limited by and a cylindrical shoulder 29, which abuts against the Fig. 4 is another detail in perspective and parttop of screw closure 18. g 7 ly in section, of the construction shown in Fig. 2. A {longit din y extending bore a f d Inthe Marshall application, Serial No. 380,564, comm nication between chamber 21 and cyl filed on February 25, 1941, there is disclosed and inder 26' t roueh o ifice 31, e endin transclaimed a novel dash pot for the control of a versely of cylind r 6. A t a sve y e te relay, a motor starting switch, a throttle,.0r the 30 met n p n 3 has a conical end p j in into like. The dash pot disclosed and claimed. in the orifice 3|, a d the amount of this projection m y prior application is effective for use in a field be regu ate y adjustment Of the sc ew-threaded identical with that of the present disclosure, but nk 33 within cylindrical p o 12 0f the a close lap fit between the cylinder and piston housing Any selected adjustment of shank shown in that application is a requisite to high 5 of p is maintained y means of a performance, and also, to the successful conflnlock-nut 3 and e escape of oil from cy ing of fluid within the dash pot, By u of cal portion i2 is prevented by means of a screwdash pot of the present invention, the necessity p Which y be sealed tightly st lockof a lap fit between a piston and a cylinder is nut 34 by means of a suitable gasket 36. avoided, and at the same time, the oil or other S e cylinder 25 and bore 39 m y be ed fluid utilized in the operation of the dash pot is within housing It by a s p drilling Operation, confined within the housing of the dash pot by s r w st pp s 31 a s t v y, y be means of a fluid-tight seal. The resultant strucp y d seal the p n nds of these memture is one that may be more cheaply and quickbers. 1y made without the sacrifice of high qualities of Wh the fi w n c nder 26 and piston operation obtained by the prior structure of ap- 23 y b as Close as desired, it need not b a plicant, lap fit, nor any closer than that usual in ordinary Having reference to the drawing, principally p Practices When the dash p is to e p- Figs. 1 and 2, there is shown at In a machined erated, the element to be time-controlled is conor cast metallic housing having a transverse cirneeted to arm and as indicated y the ows cular flange member II, and a depending cyin 2, motion of arm 2l to the left tends to lindrical portion [2. A flexible membrane or diawithdraw piston 23 from cylinder and oil is phragm member 13 of leather, rubber or a subdrawn through orifice 3i from chamber 2'! by stitute such as Neoprene, extends across the means of bore 30, and the rate at' which the oil open end of housing In and has its outer edge flows through orifice 3| depends upon the open- In motion to the right, as well as motion to v the left, the rate of movement of arm 2| is regulated by the effective opening available in orifice 3|, and thus, the dash pot of the present invention regulates the rate of movement of the element connected to arm 2| for movement in two directions.

Since the oil within the dash pot is used in a closed cycle, there can be no leakage exteriorly of housing [0, and further, if the tolerance of the fit between cylinder 26 and piston 23 is high, the leakage or flow of oil past piston 23 may be compensated for by the adjustment given to pin 32. Therefore, expensive machining and grinding operations, in order to fit piston 23 within cylinder 26 with close tolerances, are avoided, without, however, leakage or loss of control within the dash pot.

While only .one embodiment of the present invention has been shown in the drawing, it is to be understood that various changes may be made Without departing-from the scope of the present invention. For this reason, it is intended not to limit the invention by the descripion herein given as an example, but solelyby the scope of the appended claims.

What is claimed is:

1. A dash pot comprising a housing having a longitudinal cylinder, a piston therein, a rod-like extension connected to said piston, a transversely extending diaphragm of flexible material being tightly connected to said piston, means for sealing the edge of said diaphragm to said housing, a fluid chamber about said piston at one end thereof, said diaphragm forming a flexible wall ing afforded by pin 32. Movement of piston 23 thereof, a longitudinally extending bore having one end opening into said chamber and its other end opening into a transversely extending orifice in communication with said cylinder, a transversely extending metering pin extending into said orifice, and means on said rod-like extension for connecting said piston and extension to an element to be time-controlled, whereby, upon motion of said extension to withdraw said piston from said cylinder, the rate of withdrawal of said piston is governed by the rate at which fluid is drawn through said orifice into said cylinder.

.2. A dash pot for regulating the rate of movement of a time-controlled element, comprising an arm'for connection to said element, a housing, a cylinder formed therein, a piston slidably carried by said cylinder, said piston being connected to a bore connecting said orifice with said fluid chamber and a metering pin adjustably related to said orifice, whereby the rate of movement of said arm is dependent upon the rate of flow from said chamber through said orifice.

3. A dash pot for controlling the rate of movement of an element, an armfor connection to said element, a piston connected to said arm, a housing, a cylinder contained therein for receiving said piston, a flexible membrane connected 7 at its central portion to said piston and having its outer edge sealed to said housing, a recess formed at one end of said cylinder, forming, with JOHN T. MARSHALL} 

